saturated's all encompassing inclusive and exclusive bin thread

[saturated]

welcome back to the advanced epicenter of high tech experimentation


trying to hustle through the easy part of this book so I can get to some good stuff

so today they have me setting up series parallel circuits...calculating resistance..then measuring

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its pretty boring...I must have plugged and chugged a thousand of problems like this in other old textbooks
but the difference now is now I have "lab exercises"
 
also next I get to bust out some variable resistors

oh yeah...
 

[g1]

Once you learn all those equations backwards and forward, you will have a much easier time with practical applications like multiple speaker cabs with speakers of various impedances.  Then you can throw power handling into the mix and find the weakest link.   

[saturated]

the weather here has been crappy so I set out to make a little component tester
here is a schematic from a video by w2aew

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an old transformer I had was at one time showing 16.3v

so I did some math and figured i needed about 1.2M ohm

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then i went about setting everything up using the transformer, decade box, breadboard, oscilloscope

I was extremely pleased to obtain a typical y=mx+b type resistive sloped rise

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but after that nothing worked out too well.  in fact i was able to obtain a lissijou? shape and I had no capacitor connected.  yet when I tried a capacitor i just got a line.

what I really wanted was a nice L shape from a diode so I eagerly connected one but no L were to be had.

I tried different directions and ground  clips and trigger modes etc but eventually gave up.

  

[saturated]

oh yeah forgot to put this in

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[g1]

Your math is off by some factor of 10 I would think.
He has 6.3V and a 47K resistor, you have roughly 3 times the voltage, maybe should have 120K instead of 1.2M ?
Re-check your calculations.

[saturated]

thank you sir

ha ha too funny when i went back to look at my pad I turned on my calculator and it displayed the last calculation


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[saturated]

I went back to try this with 120k ohm
albeit conceding there is probably a myriad of other mitigating factors messing this up that are beyond my comprehension.
but alas it was worth a shot and thanks to G1 for pointing that out...

so off we go..dialing in 120k ohm

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and I was able to obtain some much coveted (ugly) L shaped wave form from a diode...just not in the preferred orientation

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I spent a few mins switching ends on the diode and attaching and disconnecting scope lead ground clips and couldnt really make any progress.

I imagine there are some strict parameters that need to be observed for this to work...idk

but it was a cool experiment

 
 

[saturated]

I was gonna break this down and put everything away then I remembered I had some zener diodes

so i grabbed one and tried it

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then swapping ends

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so that is cool i just dont know why everything is bassackwards

  

also i used to think these were cool heck i cant get away from them

this is what i see with the circuit open

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EDIT wondering now if i should have switched the scope probes
I did swap the transformer leads but should it really matter since its alternating current

[saturated]

I needed to color code my scope probes...

y was easy...put yellow there

for x I had a choice of blue green and pink

so as a tribute to Paul Gilbert I picked pink for X


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[saturated]

I need some ammeters for my little textbook exercises.

I have been trying to figure out the difference in ac and dc meters.

Im def old skool and have been browsing various junky analogue meters on the auction site. I like the ones that have different terminals so I can start out high and not accidentally blow it up. 
I know i can use my dmm to measure current but i really would rather use something expendable 

another problem i have with analogue is im no expert at knowing polarity so maybe if i connect it backwards it wont be good for the meter...whereas a digital would just tell me minus microamps ?

I have some old ammeters that are way to big to measure stuff like micro and milliamps.  I know I can do some calculations and add resistor shunt to make a little meter measure larger but I dont think I can go the other way...ie make for example a 15 amp simpson meter measure micro or milliamps.

peace out

 

[saturated]

last night i ordered some old millammeters 0-500 and some centered plus and minus

probably too big for what I need but i figured i would start somewhere and try not to blow em up

I really want to get a blue anatek esr meter but i am gonna make myself build one (diy esr meter) on my own first

I have looked at a few put together on videos and various schematics

I guess i need to breadboard it first then try to assemble a diy version

everything i see says i need a microammeter so i may have to scare one up

 

[saturated]

Today was somewhat exciting as it marks the first experiment to measure current

My assignment in my book was to lay out a circuit with a 1.5k resistor and measure current at 6, 12, and 18v then compare with calculated

For some reason I was really nervous shaking like a leaf idk yeah I was kinda freaked out thinking I was gonna blow something up

Especially when I had to take it up to 18v

But it went off without a hitch. All good

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[Loudthud]

Most meters have a separate input to connect one of the probes to when you measure current. There is almost always an internal fuse that will blow if you forget to move the probe back to the Voltage jack when measuring Voltage.

[saturated]

Yes sir thank you



They also had me put a 10 ohm resistor in series and measure the voltage drop across it then calculate current V/R and it was spot on to the ammeter current reading

I was impressed kinda makes you wonder why even bother with putting an ammeter in series

 

[Loudthud]

I like to use my meter's current mode to measure how much an effects pedal consumes. Simply use a 9V battery, unsnap one side of the battery connector and touch the probes between the battery terminal and the side of the connector you just unplugged.